In general, an engine of a vehicle produces vibration and noise due to reciprocating up and down movement of a piston and a connecting rod, which are provided in the engine, the moment of inertia of a crankshaft coupled to the connecting rod, which reciprocally moves up and down, and shaking occurring in a longitudinal direction of the crankshaft when the crankshaft rotates. To prevent the vibration and the noise, which result from the causes, from being transferred to a vehicle body, an engine mount formed of rubber having elasticity is mounted in the vehicle body.
Although the engine mount formed of rubber to accomplish the above purpose exhibits excellent damping performance in high-frequency and low-amplitude vibration, the engine mount is remarkably weak in low-frequency and large-displacement vibration. The engine mount may not be sufficiently damp both of the high-frequency and low-amplitude vibration and the low-frequency and large-displacement vibration.
In this regard, fluid sealed engine mounts have been used to damp wide-range vibration, which includes the high-frequency and low-amplitude vibration and the low-frequency and large-displacement vibration applied to the engine mount as the engine operates. In particular, recently, active control engine mount (ACM) systems have been suggested to prevent the reduction in noise, vibration and hardness (NVH) of a cylinder-deactivation (CDA) engine developed to improve fuel efficiency of a vehicle.
As described above, the ACM system may be employed only when the cylinders of the CDA engine are varied. The ACM system receives a cylinder pulse, a crank pulse, and a cylinder off signal from an electronic control unit (ECU), estimates the vibration based on revolutions per minute (RPM) of the engine, and damps the vibration by operating the actuator.
However, according to the related art, since the ACM system is mounted between the engine and the vehicle, the high weight of the engine fully acts on the ACM system. Therefore, according to the related art, in the ACM system, a large amount of energy is required to damp the vibration of the engine.